Process of producing bessemer steel



United States Patent 2,802,731 PROCESS OF PRODUCING BESSEMER STEELApplication December 24, 1953, Serial No. 409,383

Claims priority, application Germany August 14, 1950 1 Claims- ((11. 1-4 No Drawing.

The present invention relates to a process of producing Bessemer steeland more particularly to a process of treating iron-containing materialin a cupola furnace in such manner that the resulting molten iron isdirectly suitable for a treatment in a Bessemer furnace for theproduction of Bessemer steel in a rapid and economical manner.

The present application is a continuation-in-part of our co-pendingapplication Serial No. 239,858, filed August 1, 1951, now abandoned forProcess for Ohtaining a Pig Iron Suitable for the Bessemer Process.

According to the known methods, the calories for the production of steelin a Bessemer converter were supplied by the so-called chemical means,namely the combustion of silicon and manganese in the iron. It wastherefore necessary for the production of Bessemer steel to firstprepare a special Bessemer iron charge containing high quantities ofmanganese and silicon.

The combustion of the manganese and silicon in the Bessemer furnacesupply the calories for the production of the Bessemer steel. In orderto produce the special iron for use in the Bessemer furnace, it wasnecessary to treat an iron charge in a blast furnace in such manner thatthe resulting pig iron is chemically hot, namely it contains highquantities of silicon (about 2%) high quantities of carbon (about 4%)and high quantities of manganese (about 1.2%). Thus, the production ofBessemer steel was very expensive since it involved loss of theseelements by theoxidation thereof.

An additional disadvantage of the known processes for the P o i n of Bese er ste is the f ct th t special means had to be utilized for theremoval of impurities such as sulfur and phosphorus from the iron. Thisspecial treatment for the removal of sulfur and phosphorus had to beemployed before the iron was subjected to treatment in the Bessemerfurnace otherwise the resulting Bessemer steel would have highquantitiesof sulfur and phosphorous which adversely affects theproperties of the steel.

The only way the special treatment for the removal of sulfur andphosphor-us from the iron prior to treatment of the iron in the Bessemerfurnace could be avoided was to utilize as starting material in theblast furnace a raw material which was substantially free of sulfur andphosphorus, since blast furnace treatment could not remove the sulfurand phosphorous. However, such sulfurand phosphorous-free raw materialis relatively expensive and thereby additionally added to the cost ofthe Bessemer steel. a 7

Thus, starting from ordinary raw material, the ordinary production ofBessemer steel involves four basic treatments:

-l. treatment of the raw material in a blast furnace,

2,802,731 Patented Aug. 13, 1957 adding silicon and iron to produce aBessemer pig iron rich in silicon and manganese; 1

2. re-treatment in a cupola for a preliminary refining, namely theelimination before Bessemer treatment of a portion of the impuritiessuch as. sulfur and phosphor? ous;

3. heating in an intermediate mixer between the cupola and the converterin order to re-heat the pig iron and give to it the desired composition;and

4. treatment in an'acid Bessemerfurnace by burning the silicon andmanganese to supply calories for'the treat:

ment.

It is therefore an object of the present invention L provide a processfor producing Bessemer steel whereby the number of separate treatmentsis reduced and the process is greatly simplified.

It is another object of. the present invention to provide a process ofproducing Bessemer steel without the necessity of first producing aspecial Bessemer pig iron rich in silicon and manganese.

It is still another object of the present invention to provide a processof producing Bessemer steel whereby the raw material is in a singletreatment directly suitable for treatment in the Bessemer furnace.

A further object of the present invention comprises the utilization ofany iron-containing material a iaw material without the necessity ofenriching the raw ma: terial in silicon and manganese.

Still another object o the present invention is the attainment of greateconomy in the production of Bessemer steel while obtaining a Bessemersteel of supfi 'ior quality to that produced by known processes. 1

Other objects and advantages of the present invention will be apparentfrom the further reading of the specification and of the appendedclaims. 1

With the above Objects in view, the present invention mainly comprises aprocess of producing high quality Bessemer steel, comprising the stepsof introducing into a cupola furnace an iron containing materialalso-containing impurities with an excess of 'carbon, pas in into thethus charged cupolafurnace a heated fluid containing y e a a m turesufiicienfly h to Q ain by Oxidation of h c rbon i t arge a e pe atu ofat least 1500 C. in the cupola furnace while maintaining a reducingatmosphere therein due to the excess of carbon, thereby melting theiron-containing material containing impurities in a reducing atmospherein the .c'upola furnace while preventing formation of iron oxides,passing the molten iron-containing material in the ,cupola furnacethrough a molten basic slag at a temperature of at least 1500" C. so asto remove impurities from the molten iron-containing material and formsubstantially pure molten iron being at a temperatureof at least 1500C., and subjecting the molten iron while still at a temperature of atleast 15 00" C. to treatment in a Bessemer furnace, the temperature ofat least 1500" C. supplying the calories for the treatment in theBessemer furriace, thereby rapidly forming a high quality Bessemer steeAccording to the present invention the molten .iron leaving the cupolafurnace is sufliciently free .of impurities, due to the reducingatmosphere and basic slag at the high temperature in the cupola furnace,to be directly treated in the Bessemer furnace for conversion .toBessemer steel. In addition, due to the high temperature of at least i)"0 at which the molten iron is taken from the cupola furnace, the mo teniron can be directly treated in the Bessemer furnace, since thetemperature of 3 1500, C. is sufficient to supply all the caloriesnecessary for the Bessemer treatment. It is therefore unnecessary,according to the present invention, to add silicon and manganese to theoriginal charge in the cupola furnace in order to produce a pig ironwhich is rich in silicon and manganese.

In addition to the economy of saving silicon and manganese, this hightemperature of themolten metal leaving the cupola furnace which permitsBessemer conversion without supplying chemical heat by the burning ofsilicon and manganese, is of advantage in that there is no possibilityfor the resulting- Bessemer steel to contain silica which has adverseeffects on the properties of steel.

' It is therefore possible to produce Bessemer steel by means of theintermediate treatment in the cupola furnace according to the presentinvention starting from any raw material without the necessity of havingsilicon and manganese and without'the necessity of choosing rawmaterials which are free of impurities such as sulfur and phosphorous.

The amount of carbon in the charge is in excess of the amount normallyused for fusion processes and is in sufiicient excess to produce areducing atmosphere in the cupola furnace. The term excess of carbon istherefore meant to comprehend within its meaning an amount of carbonwhich in proportion to the amount of air or the like oxidizing agentintroduced into the cupola furnace is in such excess that a reducingatmosphere will be formed. In other words, either the carbon will not becompletely oxidized to carbon dioxide, or carbon dioxide which is formedis reduced by the excess carbon to carbon monoxide.

The desired high temperature is obtained despite incomplete combustionof the carbon by the utilization of a hot blast. Preferably air, or airenriched with oxygen, is pre-heated to a temperature of about 400600 C.before being introduced into the cupola furnace.

The reducing atmosphere in addition to causing reduction of the ironoxides to iron, is of advantage in maintaining a basic slag which isnecessary for the removal of the impurities such as sulfur andphosphorous from the iron. If necessary, basic materials such aslimestone or the like may be added to the charge to be certain that abasic slag is formed.

Although, according to the present invention, it is possible to do awaycompletely with the addition of silicon and manganese to the charge, itis possible to add these compounds to the charge in small amounts. Insuch case, because of the reducing atmosphere and the basic slag and thehigh temperature, only very little of the silicon and manganese is lostin the slag and practically the whole is incorporated into the moltenpig iron.

Although the cupola furnace may have an acid lining, it is preferred toutilize a neutral lining and most preferably a basic lining. A basicmelting can be obtained in a cupola cooled at the level of the meltingzones even where the lining of the furnace is neutral or acid, since thefurnace is charged, not only with coke and iron materials but also withlime, dolomite or other basic materials in suflicient quantities toeffect a basic melting in the cupola.

An additional advantage of the process of the present invention is thefact that the blowing period in the Bessemer converter is much shorterthan when utilizing an ordinary Bessemer pigiron. This is due to thefact that the calories are supplied mainly by the high temperature ofthe molten iron which is charged into the Bessemer converter. In theordinary Bessemer process the duration of blowing is about 1618 minutes.According to the present invention this blowing period is shortened byat least When considering large quantity production, this saving of timein addition to the possibility of utilizing cheaper raw materials, thesaving of silicon and manganese and the saving of steps, is of greatadvantage.

The Bessemer pig iron which is generally charged to a Bessemer converteraccording to theknown processes Percent C 4-4.5 Si 1-1.8 Mn 0 7 P 0.080l S 0.05 According to the present invention, on the other hand, thecarbon, silicon and manganese content of the pig iron charged into theBessemer converter may be greatly reduced, i. e., to 0.3% silicon, 0.5%manganese and 2.7% carbon.

' The following examples are given as illustrative of the presentinvention and are not to be construed as limiting the scope thereof: s

Example 1 A cupola furnace is charged with iron turnings and 20% coke,by weight. The iron turnings contain the following elements in theamounts given:

. Percent Si 2.35 Mn 0.56 P Q 0.84 S 0.08

Air, pre-heated at a temperature of about 500 C., is blown into thecupola, a reducing atmosphere being formed due to the excess of carbon,to produce a working temperature of about 1530 C. The slag is maintainedbasic by the addition of lime if necessary, and the molten pig ironwhich is withdrawn from the cupola at a temperature of about 1530 C. hasthe following composition:

Percent Si 0.3 Mn 0.5

P 0.05 S 0.06 C 2.7

This pig iron is immediately charged into Bessemer converter andsubjected to a hot blast for about 15 minutes to produce a Bessemersteel having high qualities, particularly due to the extremely lowsilica content of the steel.

Example 2 A cupola furnace is charged with 83% of a pig iron having ahigh sulfur and high phosphorous content and having approximately thefollowing composition:

Percent Si 1.55 Mn 0.32 P 1.92 S 0.72 C 3.26

with approximately 17% coke and with a small amount of calcium oxide toassure a basic slag. The charge is treated as in Example 1 utilizing ablast of air heated at a temperature of about 600 C., the temperature ofthe slag being about 1600 C. The resulting molten iron has approximatelythe following composition:

Percent Si 0.2 Mn 0.3 P 0.09 S 0.06 C 2.4

This molten iron is directly charged into a Bessemer converter andtreated therein to produce a high quality Bessemer steel.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims. p

What is claimed as new and desired to be secured by Letters Patent is:

1. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace an iron-containing materialalso containing impurities with an excess of carbon; passing into thethus charged cupola furnace a heated fluid containing free oxygen at atemperature suflicientlyhigh to obtain by oxidation of the carbon in thecharge a temperature of at least 1500 C. in said cupola furnace whilemaintaining a reducing at mosphere therein due to said excess of carbon,thereby melting said iron-containing material containing impurities in areducing atmosphere in said cupola furnace while preventing formation ofiron oxides; passing said molten iron-containing material in said cupolafurnace through a molten basic slag at a temperature of at least 1500 C.so as to remove impurities from said molten iron-containing material andform substantially pure molten iron being at a temperature of at least1500 C.; and subjecting said molten iron while still at a temperature ofat least 1500 C. to treatment in a Bessemer furnace, said temperature ofat least 1500 C. supplying the calories for said treatment in saidBessemer furnace, thereby rapidly forming a high quality Bessemer steel.

2. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace an iron-containing materialalso containing impurities with an excess of carbon; passing into thethus charged cupola furnace a fluid containing free oxygen and being ata temperature of about 400-600 C. so as to obtain by oxida tion of thecarbon in the charge a temperature of at least 1500 C. in said cupolafurnace while maintaining a reducing atmosphere therein due to saidexcess of carbon, thereby melting said iron-containing materialcontaining impurities in a reducing atmosphere in said cupola furnacewhile preventing formation of iron oxides; passing said molteniron-containing material in said cupola furnace through a molten basicslag at a temperature of at least 1500 C. so as to remove impuritiesfrom said molten iron-containing material and form substantially puremolten iron being at a temperature of at least 1500 C.; and subjectingsaid molten iron while still at a temperature of at least 1500 C. totreatment in a Bessemer furnace, said temperature of at least 1500 C.supplying the calories for said treatment in said Bessemer furnace,thereby rapid, ly forming a high quality Bessemer steel.

3. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace a charge being substantiallyfree of silicon and mangan-ese and including an iron-containing materialalso containing impurities with an excess of carbon; passing into thethus charged cupola furnace a heated fluid containing free oxygen at atemperature sufliciently high to obtain by oxidation of the carbon inthe charge a temperature of, at least 1500 C. in said cupola furnacewhile maintaining a reducing atmosphere therein due to said excess ofcarbon, thereby melting said iron-containing material containingimpurities in a reducing atmosphere in said cupolafurnace whilepreventing formation of iron oxides; passing said molten iron-containingmaterial in said-cupola furnace through a molten basic slag at atemperature of at ,least 1500 C. .so as to remove impurities from saidmolten iron-containing material and form substantially pure molten ironbeing at a temperature of at least 1500 C.; and subjecting said molteniron while still at a temperature of at least 1500 C. to treatment in aBessemer furnace, said temperature of at least 1500 C. supplying thecalories for said treatment in said Bessemer furnace, thereby rapidlyforming a high quality Bessemer steel.

4. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace an iron-containing materialalso containing sulfur and phosphorous as impurities with an excess ofcarbon; passing into the thus charged cupola furnace a heated fluidcontaining free oxygen at a temperature sufliciently high to obtain byoxidation of the carbon in the charge a temperature of at least 1500 C.in said cupola furnace while maintaining a reducing atmosphere thereindue to said excess of carbon, thereby melting said iron-containingmaterial containing sulfur and phosphorous as impurities in a reducingatmosphere in said cupola furnace while preventing formation of ironoxides; passing said molten iron-containing material in said cupolafurnace through a molten basic slag at a temperature of at least 1500 C.so as to desulfurize and dephosphorize said molten ironcontainingmaterial and form substantially pure molten iron being at a temperatureof at least 1500 C.; and subjecting said molten iron while still at atemperature of at least 1500 C. to treatment in a Bessemer furnace, saidtemperature of at least 1500 C. supplying the calories for saidtreatment in said Bessemer furnace, thereby rapidly forming a highquality Bessemer steel.

5. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola having a neutral lining a chargebeing substantially free of silicon and manganese and including aniron-containing material also containing sulfur and phosphorous asimpurities with an excess of carbon; passing into the thus chargedcupola furnace a heated fluid containing free oxygen at a temperaturesufficiently high to obtain by oxidation of the carbon in the charge atemperature of at least 1500 C. in said cupola furnace while maintaininga reducing atmosphere therein due to said excess of carbon, therebymelting said iron-containing material containing sulfur and phosphorousas impurities in a reducing atmosphere in said cupola furnace whilepreventing formation of iron oxides; passing said molten iron-containingmaterial in said cupola furnace through a molten basic slag at atemperature of at least 1500 C. so as to desulfurize and dephosphorizesaid molten ironcontaining material and form substantially pure molteniron being at a temperature of at least 1500 C.; and subjecting saidmolten iron while still at a temperature of at least 1500 C. totreatment in a Bessemer furnace, said temperature of at least 1500 C.supplying the calories for said treatment in said Bessemer furnace,thereby rapidly forming a high quality Bessemer steel.

6. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace having a basic lining acharge being substantially free of silicon and manganese and includingan ironcontaining material also containing sulfur and phosphorous asimpurities with a excess of carbon; passing into the thus charged cupolafurnace a heated fluid .c0ntaining free oxygen at a temperaturesufliciently high to obtain by oxidation of the carbon in the charge atemperature of at least 1500 C. in said cupola furnace while maintaininga reducing atmosphere therein due to said excess of carbon, therebymelting said iron-containing material containing sulfur and phosphorousas impurities in a reducing atmosphere in said cupola furnace Whilepreventing formation of iron oxides; passing said molten iron-containingmaterial in said cupola furnace through a molten basic slag ,at atemperature of at least 1500 C. so as to desulfurize and dephosphorizesaid molten ironcontaining material and form substantially pure molteniron being at a temperature of at least 1500 C.; and subjecting saidmolten iron while still at a temperature of at least 1500 C. totreatment in a Bessemer furnace, said temperature of at least 1500 C.supplying the calories for said treatment in said Bessemer furnace,thereby rapidly forming a high quality Bessemer steel. 7. A process ofproducing high quality Bessemer steel, comprising the steps ofintroducing into a cupola furnace an iron-containing material alsocontaining impurities with an excess of carbon; passing into the thuscharged cupola furnace heated air enriched with oxygen and being at atemperature of about 400-600 C. so as to obtain by oxidation of thecarbon in the charge a temperature of at least 1500 C. in said cupolafurnace while maintaining a reducing atmosphere therein due to saidexcess of carbon, thereby melting said iron-containing materialcontaining impurities in a reducing atmos phere in said cupola furnacewhile preventing formation of iron oxides; passing said molteniron-containing material in said cupola furnace through a molten basicslag at a temperature of at least 1500 C. so as to remove impuritiesfrom said molten iron-containing material and and form substantiallypure molten iron being ata temperature of at least 1500 C.; andsubjecting said molten iron while still at a temperature of at least1500 to treatment in a Bessemer furnace, said temperature of at least1500 C. supplying the calories for said treatment in said Bessemerfurnace, thereby rapidly forming a high quality Bessemer steel.

8. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace an iron-containing materialalso containing impurities with an excess of carbon and a quantity ofbasic materials sufiicient to form a basic slag; passing into the thuscharged cupola furnace a heated fluid containing free oxygen at atemperature sufficiently high to obtain by oxidation of the carbon inthe charge a temperature of at least 1500 C. in said cupola furnacewhile maintaining a reducing atmosphere therein due to said excess ofcarbon, thereby melting said iron-containing material containingimpurities in a reducing atmosphere in said cupola furnace whilepreventing formation of iron oxides; passing said molten iron-containingmaterial in said cupola furnace through a molten basic slag at atemperature of at least 1500 C. so as to remove impurities from saidmolten iron-containing material and form substantially pure molten ironbeing at a temperature of at least 1500 C.; and subjecting said molteniron while still at a temperature of at least 1500 C. to treatment in aBessemer furnace, said temperature of at least 1500 C. supplying thecalories for said treatment in said Bessemer furnace, thereby rapidlyforming a high quality Bessemer steel.

9. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace iron ore also containingimpurities with an excess of carbon; passing into the thus chargedcupola furnace a heated fluid containing free oxygen at a temperaturesufficiently high to obtain by oxidation of the carbon in the charge atemperature of at least 1500 C. in said cupola furnace while maintaininga reducing atmosphere therein due to said excess of carbon, therebymelting said iron-containing material containing impurities in areducing atmosphere in said cupola furnace while preventing formation ofiron oxides; passing said molten iron ore in said cupola furnace througha molten basic slag at a temperature of at least 1500 C. so as to removeimpurities from said molten iron ore and form substantially pure molteniron being at a temperature of at least 1500 C.; and subjecting saidmolten iron while still at a temperature of at least 1500 C. totreatment in a Bessemer furnace, said temperature of at least 1500 C.supplying the calories for said treatment in said Bessemer furnace,thereby rapidly forming a high quality Bessemer steel.

10. A process of producing high quality Bessemer steel, comprising thesteps of introducing into a cupola furnace scrap iron also containingimpurities with an excess of carbon; passing into the thus chargedcupola furnace a heated fluid containing free oxygen at .a temperaturesufficiently high to obtain by oxidation of the carbon in the charge atemperature of at least 1500 C. in said cupola furnace while maintaininga reducing atmosphere therein due to said excess of carbon, therebymelting said scrap iron containing impurities in a reducing atmospherein said cupola furnace while preventing formation of iron oxides;passing said molten scrap iron in said cupola furnace through a moltenbasic slag at a temperature of at least 1500 C. so as to removeimpurities from said molten scrap iron and form substantially puremolten iron being at a temperature of at least 1500 C.; and subjectingsaid molten iron while still at a temperature of at least 1500 C. totreatment in a Bessemer furnace, said temperature of at least 1500 C.supplying the calories for said treatment in said Bessemer furnace,thereby rapidly forming a high quality Bessemer steel.

11. A process of obtaining a pig iron suitable for charging a Bessemerconverter which comprises charging a cupola with a charge consistingessentially of an iron containing material and an excess of carbonsuflicient to form in said cupola a reducing atmosphere, subjecting saidcharge to a'hot blast of about 400600- C. and heating said charge to atleast 1500 C. until a molten pig iron containing a maximum of 0.3%silicon and 0.5% manganese is formed, and recovering said molten pigiron having a minimum working temperature of about 1500 C. andcontaining said amounts of silicon and manganese. i

12. A process of obtaining a pig iron suitable for charging a Bessemerconverter which comprises charging a cupola with a charge consistingessentially of an iron scrap and an excess of carbon sufiicient'to formin said cupola a reducing atmosphere, subjecting said charge to a hotblast of about'400600 C. and heating said charge to at least 1500 C.until a molten pig iron containing a maximum of 0.3% silicon and 0.5%manganese is formed, and recovering said molten pig iron having aminimum working temperature of about 1500 C. and containing said amountsof silicon and manganese.

13. A process of obtaining a pig iron suitable for charging a Bessemerconverter which comprises charging a cupola with a charge consistingessentially of an iron containing material and 17-20% coke sufficient toform in said cupola a reducing atmosphere, subjecting said charge to ahot blast of about 400-600 C. and heating said charge to at least 1500C. until a molten pig iron containing a maximum of 0.3% silicon and 0.5manganese is formed, and recovering said molten pig iron having aminimum working temperature of about 1500 C. and containing said amountsof silicon and manganese.

14. A process of obtaining a pig iron suitable for charging a Bessemerconverter which comprises charging a cupola with a charge consistingessentially of an iron ore and an excess of carbon sufficient to form insaid cupola a reducing atmosphere, subjecting said charge to a hot blastof about 400600 C. andheating said charge to at least 1500 C. until amolten pig iron containing a maximum of 0.3% silicon and 0.5% manganeseis formed, and recovering said molten pig iron having aminimum workingtemperature of about 1500 C. and containing said amounts of silicon andmanganeses.

15. A process of obtaining a pig iron which comprises charging a cupolawith a charge consisting essentially of an iron containing materialconsisting at least partly of scrap iron and an excess of carbonsuflicient to form in said cupola a reducing atmosphere, subjecting saidcharge to a hot blast of about 400-600" C. and heating said charge toat'least 1500 C. until a molten pig iron 9 a 10 containing a maximum of0.3% silicon and 0.5% man- References Cited in the file of this patentganese is formed, and recovering said molten pig iron UNITED STATESPATENTS having a minimum working temperature of about 1500 C. andcontaining said amounts of silicon .and manga- 2669446 Doat 1954 nese. 6OTHER REFERENCES Manufacture of iron and steel, vol. II, SteelProduction, pages 4 and 5,. edited by Bashforth, published in 1951 byChapman and Hall, Limited, London, England.

1. A PROCESS OF PRODUCING HIGH QUALITY BESSEMER STEEL, COMPRISING THESTEPS OF INTRODUCING INTO A CUPOLA FURNACE AN IRON-CONTAINING MATERIALALSO CONTAINING IMPURITIES WITH AN EXCESS OF CARBON; PASSING INTO THETHUS CHARGED CUPOLA FURNACE A HEATED FLUID CONTAINING FREE OXYGEN AT ATEMPERATURE SUFFICIENTLY HIGH TO OBTAIN BY OXIDATION OF THE CARBON INTHE CHARGE A TEMPERATURE OF AT LEAST 1500*C. IN SAID CUPOLA FURNACEWHILE MAINTAINING A REDUCING ATMOSPHERE THEREIN DUE TO SAID EXCESS OFCARBON, THEREBY MELTING SAID IRON-CONTAINING MATERIAL CONTAININGIMPURITIES IN A REDUCING ATMOSPHERE IN SAID CUPOLA FURNACE WHILEPREVENTING FORMATION OF IRON OXIDES; PASSING SAID MOLTEN IRON-CONTAININGMATERIAL IN SAID CUPOLA FURNACE THROUGH A MOLTEN BASIC SLAG AT ATEMPERATURE OF AT LEAST 1500*C. SO AS TO REMOVE IMPURITIES FROM SAIDMOLTEN IRON-CONTAINING MATERIAL AND FROM SUBSTANTIALLY PUR MOLTEN IRONBEING AT A TEMPERATURE OF AT LEAST 1500*C.; AND SUBJECTING SAID MOLTENIRON WHILE STILL AT A TEMPERATURE OF AT LEAST 1500* C, TO TREATMENT IN ABESSEMER FURNACE, SAID TEMPERATURE OF AT LEAST 1500*C. SUPPLYING THECALORIES FOR SAID TREATMENT IN SAID BESSEMER FURNACE, THEREBY RAPIDLYFORMING A HIGH QUALITY BESSEMER STEEL.